CLEVELAND, Ohio (CNN) -- With the Democratic race extremely tight, the party's superdelegates -- the 800 or so unpledged elected officials and party members -- are facing growing racial pressure, and even threats, to back Sen. Barack Obama.

Sen. Barack Obama has won the past 11 contests and leads in the overall delegate count.

In Cleveland, Ohio, a predominantly African-American city, black voters are hoping Obama becomes the next president of the United States. But that's making it very difficult for the people who represent them.

Cleveland City Councilman Kevin Conwell, a onetime supporter of Sen. Hillary Clinton, is switching sides to the Obama camp.

It had little to do with Clinton and everything to do with pressure from people who voted him into office.

"I thought that I would never see an African-American going for president of the United States of America. This is a dream and you need to get on the right side of history, and my residents want me to be a part of this dream," Conwell said.

Other nationally prominent politicians have experienced similar pressure. Three African-American superdelegates have also defected, including Georgia Rep. John Lewis, a longtime Clinton ally. Watch Lewis endorse Obama »

"There comes a time when you have to make a decision. As a superdelegate to the Democratic Convention ... I will be casting my vote for Barack Obama," Lewis told WSB-TV in Atlanta Wednesday.

"With all due respect to my colleagues, whoever you are, I firmly believe if you don't have loyalty and integrity, what do you have? ... I am a woman of my word. I will not leave her," said Ohio Rep. Stephanie Tubbs Jones.

Neither will California Rep. Diane Watson, though she said she's received not only pressure, but also threatening e-mails.

"We can disagree. But I don't think that's a cause for viciousness and for launching a campaign against me," Watson said.

Their continued loyalty is no doubt a plus for the Clinton campaign -- although her campaign has said Clinton understands.

"People have to make their own decisions and you have to respect their decisions and say, OK, I have to reach that many more people and ask for their respect," said Ann Lewis, a senior adviser to Clinton.E-mail to a friend